In general, in the manufacturing of a gear, a predetermined gear blank is subjected to gear cutting to form a gear, and then heat treatment is performed on this cut gear. However, the tooth surface of the gear may not have a dimensional accuracy as required in some cases since performing the heat treatment on the gear as mentioned above causes strain and the like in the gear due to thermal stress. In such a case, the tooth surface of the gear is ground after the heat treatment to improve the dimensional accuracy.
To grind the gear, a grinding wheel for gear grinding is used. To dress this grinding wheel for gear grinding, a dressing gear is used as one of dressing tools. A dressing method using a dressing gear as above is disclosed in Patent Document 1, for example. Specifically, this Patent Document 1 discloses a dressing method in which a threaded grinding wheel for crown gear grinding and an externally-toothed dressing gear are rotated in synchronization with each other in a state of meshing with each other, while the dressing gear is moved in such a way as to traverse the threaded grinding wheel over the entire area thereof in the grinding wheel axis direction about the rotation axis of a pinion which can mesh with the crown gear.